In winter, early in the morning, there was sometimes observed a low cloud layer near the coast of Ishikari Bay, Hokkaido. Still and motion pictures of this type of cloud layer were taken from the top of Mt. Teine. The results indicate that these clouds seem to have been caused by the mixing of relatively warm air over the bay and cold air flowing out from the Ishikari Plain. These "coastal clouds" occurred only on a clear morning which follows a clear night, and they were found only over the coast of the bay. The observed clouds were small in scale, and it did not produce precipitation. It is expected, however, that such clouds may occur on a larger scale in other places, and that it may produce precipitation even if there is no front nor mountain.
Rainwater has been collected separately according to their drop sizes by using a raindrop spectrograph as reported by Bowen and Davidson (1951). Chemical compositions have been measured and are compared with intensity of rainfalls at each range of drop size. In the case of large raindrops, it has been found that the concentration of chloride in rainwater increases with increase in intensity of rainfall. In the case of small raindrops, it has been found that the concentration of chloride in rainwater decreases with increase in intensity of rainfall. In some samples of rainwater, the concentration of deuterium was measured. In order to estimate the amount of chloride collected as dry fallout, distilled water has been exposed every time in the air stream of the raindrop spectrogaph. The contamination of the exposed distilled water was chemically analysed, and a correction of chloride content in rainwater was made by substracting the amount of the chloride content of contamination from the value of the chloride content in the rainwater in collectors.
The three-dimensional mesoscale structure of a huge stratiform radar rainband is analysed in conjunction with aerological and surface observations. The analysis reveals that a deep cold air extending vertically above the 200mb level lay along the centerline of the rainband, and that the vertical airflow was downward along the front side of the cold air and upward along the back. In other words, the vertical circulation was direct in the forward part of the rainband and was indirect in the backward. The deep cold air seems to be a result of the following two effects, adiabatic cooling of the ascending current through stable stratification, and evaporation of precipitation falling through the descending current. The indirect ascending current is considered to be induced by the strong southerly winds being blocked by the descending air in the westerlies (the direct circulation). The analysis also suggests how the wind field, stability, horizontal temperature gradients and other factors act to produce a persistent rainband in a stably stratified atmosphere.
The properties of power-spectra and cross-spectra of horizontal turbulence in high winds are mainly described. The data of wind were obtained from the observations made with the use of cup anemometers which were mounted at five elevations of 26, 67, 107, 173 and 253 meters on the Tokyo-Tower. The maximum of mean wind speed in the data was 33.2 m/s at the elevation of 253 meters. Tentative conclusions are as follows : (1) It seemed that the power-spectral curves were rather broader than Davenport's formula at the peak of curves, and belonged to “over land trajectory type” designated by Panofsky and McCormick. (2) The spatial structure of turbulence was examined from the coherence between velocities at each pair of neighbouring stations. The structure showed that the spatial correlation of velocities became zero, when the ratio of vertical separation to the wave length was 0.2. (3) Phase spectra between velocities at each pair of the stations showed an interesting pattern:The fluctuation of the winds became out of phase at the frequency where the turbulence energy had a maximum value (the frequency, was about 0.02c/s). (4) The rate of dissipation of turbulence energy and nondimensional constant C2 in the spectral equation were obtained from both the profile of wind velocity and the onedimensional energy spectrum.